About as overstable as the Tilt. Nuf said. :D 

The Chup is a very OS fairway driver. I have it in both Bravo and Glow plastic. The glow will fly a bit straighter before fading. I only throw on forehand and typically get a large pushing skip in all but the thickest grass. Don't get me wrong though, you're not going to get a ton of distance with this one but you can release it on a large amount of anhyzer not having to worry about turning it over. It will flip up quickly and fade out as expected. 

It is a very good disc but a utility one. It makes my Splice look like a Teebird. If you want something in between a tilt and a splice this is it. I forehand this thing and it literally goes from anhyzer to straight up and down fast.

The Chupacabra in Bravo, is one of the most stable discs in the category out of the box. I expect it to beat in with time. If you're looking at your flat top metal flake firebird or meta splice wishing it was more OS .... here's your answer.